docs: def sentences(self):
          """Return a list of Sentences that make up this text passage."""
          sents = []
          spans = self.sentence_tokenizer.span_tokenize(self.text)
          for span in spans:
              sent = Sentence(
                  text=self.text[span[0]:span[1]],
                  start=span[0],
                  end=span[1],
                  word_tokenizer=self.word_tokenizer,
                  lexicon=self.lexicon,
                  abbreviation_detector=self.abbreviation_detector,
                  pos_tagger=self.pos_tagger,
                  ner_tagger=self.ner_tagger,
                  parsers=self.parsers,
                  document=self.document
              )
              sents.append(sent)
          return sents